(a) Field of the Invention
This invention relates to well drilling by the rotary method, and more particularly to ultrasonic monitoring of mud level in the drilling mud return line.
(b) Description of the Prior Art
The use of sound to determine the level of liquid in a tank is disclosed by U.S. Pat. Nos.
2,943,296--Fryklund (filed 1955) PA1 3,184,969--Bolton (filed 1963) PA1 4,000,650--Snyder (filed 1975) PA1 2,914,686--Clements et al (filed 1953) PA1 2,927,301--Booth et al (filed 1954) p1 3,100,023--Clements (filed 1959) PA1 3,726,136--McKean et al (filed 1970) PA1 3,821,726--Chang (filed 1972)
The use of sound to determine the level of liquid in a well is disclosed by U.S. Pat. Nos.
An apparatus combining a return mud flowline transducer, a mud pit level transducer and pump pressure transducer is disclosed in U.S. Pat. No.
The flowline transducer is actuated by a paddle on the flowline; the pit level transducer is actuated by a float.
The use of piezoelectric transducers strapped to mud inlet and return lines as vibration detectors for early warning of blowouts is disclosed in U.S. Pat. No.
In a preprint of paper number SPE 6023 of the Society of Petroleum Engineers of the American Institute of Mining Metallurgical and Petroleum Engineers entitled "Selection and Sensitivity Requirements for Blowout Control Detection Instruments" by Albert K. Dittmer and F. J. Fisher, copyright 1976 it is said:
"In blowout control and prevention planning, the prime detection instrument needs to be designed and its minimum sensitivity specified. *** Through use of a computer program *** comparisons are made of detection instrument alternatives."